gprof question

[Dave Cottingham]

What does it mean when the total CPU time reported by gprof is quite
different from the total CPU time measured by the operating system?  

On a program I'm trying to speed up, gprof output gives a total
cumulative time of 536 seconds, but the OS said about 10 times that long
(and my watch is in general agreement with the OS).  Is this a bug?  Or
does this just tell us that 90% of the time was spend in library
routines and is therefore off the books?  If the latter, is there any
way to get the time in library routines charged to the caller?

This is on Redhat 8.0, which uses gcc 3.2, and gprof 2.13.90.0.2.

I'd be appreciative for any insights anyone can provide.

Thanks,
Dave Cottingham